Prognostic Impact of Late Gadolinium Enhancement on Major Adverse Cardiovascular Events and Time‐Varying Attenuation of Risk in Dilated Cardiomyopathy

OBJECTIVES: To investigate the prognostic value of late gadolinium enhancement (LGE) extent for major adverse cardiovascular events (MACE) in dilated cardiomyopathy (DCM) patients and characterize the dynamic pattern of its risk effect over time. METHODS: We retrospectively enrolled patients who underwent Cardiac Magnetic Resonance (CMR) between 2020 and 2024, with MACE (cardiac death, heart failure re-hospitalization, or sustained ventricular arrhythmia) as the endpoint. Patients were stratified by MACE occurrence. Schoenfeld residual testing showed borderline deviation of the proportional hazards (PH) assumption for LGE extent (LV mass percentage). Thus, a time-dependent Cox model (Extended Cox PHs Model) with an LGE extent × follow-up time interaction term was built to assess dynamic hazard ratio changes, and independent MACE risk factors were identified. RESULTS: Among 173 DCM patients (age 47 ± 15 years, 105 males), 46 (26.6%) experienced MACE after a mean follow-up of 27 ± 16 months. The time-dependent Cox model identified LGE extent (baseline HR: 1.243, 95% CI: 1.162-1.329, p < 0.001), the LGE extent × time interaction (HR: 0.993, 95% CI: 0.989-0.997, p = 0.001), and LV end-diastolic volume index (LVEDVi; HR = 1.008, 95% CI: 1.003-1.014, p = 0.001) as independent MACE predictors. Notably, the risk effect of LGE extent demonstrated time-dependent attenuation. CONCLUSION: LV LGE extent and LVEDVi independently predict MACE in DCM patients. The early prognostic value of LGE extent suggests a critical time window for early fibrosis intervention.